Gear pump with pressure loaded end plate and with pressure loaded peripheral tooth sealing means



Feb. 2, 1960 D. LORENZ 2,923,249

GEAR PUMP WITH PRESSURE LOADED END PLATE AND WITH PRESSURE LOADED PERIPHERAL TOOTH SEALING MEANS Filed Feb. 4, 1954 2 Sheets-Sheet 1 Dana/a L. Lorenz ZZLHE' 2,923 END PLATE AND WITH 0TH SEALING MEANS Feb. 2, 1960 D. L. LORENZ GEAR PUMP WITH PRESSURE LOADED PRESSURE LOADED PERIPHERAL TO Flled Feb 4 1954' 2 Sheets-Sheet 2 Eva 121's? Donald L. Lorenz iinited States Patent GEAR PUMP WITH PRESSURE LOADED END PLATE AND WITH PRESSURE LOADED PERIPEERAL TOOTH SEALING MEANS Donald L. Lorenz, Euclid, Ohio, assignor to Thompson Rama Wooldridge Inc., a corporation of Ohio Application February 4, 1954, Serial No. 408,210

7 Claims. ((11. 103- 126) This invention relates generally to pumping apparatus and more paritcularly relates to a gear pump having movable peripheral tooth sealing means pressure loaded inwardly adjacent the outlet side of the pump, thereby minimizing journal loading due to pressurization in the discharge of the pump while maintaining proper tooth sealing for pumping purposes.

According to the general principles of the present invention, full discharge pressure in a gear pump is limited to a predetermined number of teeth adjacent the discharge port by providing movable peripheral tooth sealing means loaded inwardly by .pump generated pressure. All of the other teeth are arranged to seal only at low pressure. By such provision journal loading is minimized.

It is further contemplated in accordance with the principles of the present invention to provide peripheral tooth sealing means in combination with pressure loaded end plate means utilized for confining fluid in the spaces between the gear teeth. Pressure chambers are located in the pump behind the end plate means as Well as behind the peripheral tooth sealing means so that pump generated pressure may be effectively utilized to pressure load the movable sealing components.

It is an object of the present invention to provide a pump having movable sealing means loaded inwardly of the periphery of a pumping chamber to engage a rotary fluid displacement means.

Another object of the present invention is to provide means for reducing and minimizing journal loading due to pressurization in the discharge zone of a pump.

Another object of the present invention is to provide movable peripheral tooth sealing .means on the outlet side of a gear pump to confine the pressure distribution area of the pump to a predetermined number of gear teeth.

Many other objects, advantages and additional features of the present invention will become manifest to the person skilled in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings in which a preferred structural embodiment of a pump incorporating the principles of the present invention is shown by way of illustrative example.

As shown on the drawings:

Figure 1 is an end elevational view of a pump provided in accordance with the principles of the present invention;

Figure 2 is a cross sectional view of the pump shown in Figure 1 taken substantially on line -IIII of Figure 1;

Figure 3 is a cross sectional view taken substantially on line IHIII of Figure 1;

Figure 4 is a fragmentary cross-sectional view taken substantially on line IVIV of Figure 3;

Figure 5 is a view similar to Figure 4 but showing an alternative modification provided in accordance with the principles of the present invention;

Figure 6 is an elevational view of the movable-pressure ji atented Feb. 2, 1980 2 c loaded bushing provided ,in accordance with the principles of the present invention; and

Figure 7 is a cross-sectional view of a stationary bushing provided in accordance with the principles of the present invention.

As shown on the drawings:

The pump of the present invention is indicated generally by the reference numeral 10 and includes a body member 11 cooperating with a cover member 12, the body member 11 and the cover member 12 together comprising a pump casing which is held in assembly by a plurality of suitable fasteners indicated at 13.

The body member 11 is provided with a pair of bores 14 and 16 adapted to receive the stub ends of a pair of gear shafts 17 and 18, respectively. Between each stub end of the shafts 17 and 18 and the body member 11 is provided a bushing member 19 and 20, respectively, formed of a suitable bearing material and providing a journal surface for the respective shafts axially grooved as at in order to journal the shafts 17 and 18 for rotation within the pump casing.

The body member 11 is further provided with a generally figure 8-shaped cavity or chamber indicated at 21 which lies adjacent the bores 14 and 16, the figure 8- shaped chamber 21 more particularly comprising a pair of overlapping or intersecting bores.

Each of the fixed bushings 19 and 20 is provided with a radially outwardly extending flange portion 22 and 23 and each flange portion 22 and 23 provides a rear shoulder indicated by the common reference numeral 24 which engages an adjacent shoulder provided by the body member 11 and a front sealing face indicated by the common reference numeral 26 which engages the adjoining side face of a corresponding gear, including the driver gear 27 on the shaft 17 and the driven gear 28 on the shaft 18.

The cover member 12 is provided With a bore 30 which receives the other end of the shaft 18, a movable bushing 31 being provided between the cover member 12 and the shaft 18. The movable bushing 31 is made of a suitable bearing material and has a tubular extension 32 which forms a journal support between the shaft 18 and the cover member 12. The covermember 12 is provided with an annular groove 33 receiving an 0 ring type sealing member 34 for establishing a seal along the length of the tubular extension 32,

The bushing member 31 is provided with a radially extending flange 36 providing a front sealing face 37 which engages an adjoining side face of the driven gear 28. The back face of the flange 36 is indicated at 38 and is spaced from an adjoining wall 39 of the cover member to form together with the cover member a pressure control chamber 40. Pump generated pressure is communicated to the pressure control chamber 40 in any suitable manner, for example, a passageway 41 may be provided through the bushing flange 36 as is shown in Figure 6 of the drawings so that the movable bushing 31 will be pressure loaded into proper sealing engagement with the gear 28.

To effect initial loading of the movable bushing 31 against the gear side face, a figure S-shaped spring indi- O-ring sealing member 46 engaging the peripheral surface of the flange 36 on the movable bushing 31.

The covermember 12 is further provided with a bore 50 opening outwardly of the pump casing through a boss 51 formed on the cover member 12." The boss 51 is provided with an enlarged counterbore as at 52 and the shaft 17 extends outwardly through the counterbore 52 and provides a-coupling portion 53 which may be connected to a suitable source of power (not shown). A shaft seal indicated generally at 54 is located in the counterbore 52 between the cover member 12 and the shaft It will be understood that thebore 50 behind the movable bushing may be communicated with a source of low pressure so as to protect the seal 54.

It will also be understood that the bore 50 is provided with a movable bushing member which develops the functions in regard to the driving gear 27 as the movable bushing member 31 with respect to the driven gear 28 and, accordingly, since these bushings are similar, like reference numerals have been applied to both bushing members for purposes of convenience and understanding the principles of the present invention.

As is more clearly indicated in Figures 1, 3, 4 and 5, the pump is provided with an inlet 56 and an outlet 57.

According to the principles of the present invention, the pump is further provided with movable pressure loaded wall means peripherally adjacent the pumping cavity and spaced from adjoining portions of the pump casing or housing to form a pressure chamber com municating with a source of high pressure so that the wall means may be loaded inwardly for peripheral tooth sealing.

One of the objectives attained by the provision of such an arrangement is the reduction and minimization of .the journal loading due to pressurization in the discharge portions of the pump. In effecting this objective, the normal sealing zone of the pump on the inlet side of the pump between the outside diameter of the gear and the inside diameter of the pumping cavity was relocated so that the pressure distribution area onthe discharge side of the pump is minimized. Accordingly, the movable pressure loaded wall means are located on the discharge side of the pump casing or housing to seal in this specified minimum area, thereby to provide a minimized pressure distribution area and still maintain proper tooth sealing against the walls of the pumping cavity.

Referring specifically to Figure 4, it will be noted. that I 61 of the pumping cavity 21 from the discharge side of the pump 10 toward the inlet side thereof. There is thus provided a thin wall flexible or movable wall means 62 which is movable inwardly under pressure loading elfected by the communication of pump generated discharge pressure into the recess from the pump outlet 57.

As is clearly shown in Figure 4, the driver gear indicated generally at 27 is provided with a plurality of circumferentially spaced teeth 63. In accordance with the principles of the present invention, the sealing arrangement provides adequate sealing of the tips of the gear teeth 63 by limiting full discharge pressure to only those two teeth adjacent to the discharge port or outlet 57. To facilitate understanding of this statement, these two teeth are indicated on Figure 4 by the reference numerals 66 and 67 respectively, the unbalanced load area prescribed by the teeth 66 and 67 being bracketed by dashed line prescribing a dimension indicated at the arrow (D-5! The spaces between all of the other teeth on the gear 27 away from the discharge port or outlet 57 is communicated with a source of low pressure, which in this instance comprises the inlet port orinlet 56. To effect such communication, the face 37 of the movable bushings 31 is provided with an annular groove 68 which is spaced inwardly from the periphery thereof but which is spaced outwardly of the rootdiameter of the gear teeth 63 thereby to intercommunicate the spaces between the teeth 63 and also to communicate all of these spaces with the inlet port or inlet 56. The arrangement thus provided affords balanced journal loading since full discharge pressure need be sealed only at the area lying between the two teeth adjacent the discharge port or outlet 57.

As indicated in the drawings of Figure 4, the driven gear 28 is peripherally sealed by movable wall means similarly constructed to those described in connection with the driver gear 27. Because of the similarities in structure and operation, like reference numerals have been applied wherever appropriate for convenience in understanding the principles of the present invention.

The embodiment of Figure 5 is similar to the form of the invention already described, however, this embodiment shows the principles of the invention as applied to a pump equipped with a separate liner 70 providing the walls of the pumping cavity 21. The liner 70 is of a general figure 8-shaped configuration so as to conform to the shape of the pumping cavity or pumping chamber 21. Thebody member 11 of the pump 10 is provided with arcuate recesses 71 and 72 which are generally concentrically outwardly spaced of the pumping cavity 21 so as to provide a thin walled portion 73 adjacent the liner '70 at the discharge side of the pump. Discharge pressure generated by the pump is communicated to the recess 71 so as to flex or bend the thin walled portion 73 inwardly, thereby urging the adjacent portions of the liner 70 into sealing engagement with the peripheral tips of the gears 27 and 28 respectively.

As is indicated by dotted lines in Figure 5, the outlet port or outlet 57 is recessed as at 76 to extend through an area approximately equal to the distance slightly less than the distance between the tips of three circumferentially spaced teeth on the gears 27 and 28 and, accordingly, it is within this area that full discharge pressure must be sealed.

With this form of the invention, the liner 70 extendsaround the complete periphery of the pumping chamber 21 and, accordingly, it is necessary to provide a form of discharge porting which will not interfere with the sealing means. As shown in Figure 5 accordingly, the bearing flanges are provided with a discharge port indicated as 77 thereby permitting the discharge fluid to flow axially through the bearing flanges at the discharge area adjacent the mesh of the gears 27 and 28.

In regard the specific bushing structures illustrated in Figures 6 and 7, it should be noted that on the movable bushings 31 the tubular extensions 32 are offset towards the inlet side of the pump, thereby providing a back face 38 subject to pressures developed in the pressure control chamber 40 which varies proportionately in area from the inlet to .the outlet sides of the pump whereby unequal ized by the formation of the annular groove 68 in the sealing faces 26 thereof to intercommunicate the tooth spaces and to communicate low inlet pressure to the tooth spaces, but the journal surface thereof is characterized by the formation of one or more axially extending grooves 80 which assist in keeping the journal surface flooded with coolant and lubricant.

Although various minor structural modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my'invention:

1. A gear pump comprising a housing having an inlet port and an outlet port and providing intersecting bores forming a pumping cavity, said cavity having a discharge zone remote from said inlet and communicating with said outlet, movable wall means peripherally adjacent said bores at said discharge zone and spaced from adjoining portions of said housing to form a pressure chamber, meshing toothed gears in said bores for moving fluid from said inlet port to said outlet port, means formed to communicate pump generated pressure to said pressure chamber to load said wall means inwardly for peripheral tooth loading, and end plate means movably mounted in said housing and having a rear pressure face spaced from an adjoining wall of said housing to form a pressure chamber communicating with pump discharge and having a front pressure face for sealing and engaging an adjoining side face of said gears.

2. A gear pump as defined in claim 1, said housing having arcuate recesses formed therein concentrically outwardly of said intersecting bores, thereby to form said movable wall means peripherally adjacent said bores and spaced from adjoining portions of said housing to form the said pressure chamber.

3. A gear pump as defined in claim 1, and means communicating the spaces between all of the gear teeth except the two gear teeth immediately adjacent the outlet port to inlet pressure, thereby limiting fio'w discharge pressure sealing by said movable wall means to the area prescribed between said two gear teeth.

4. A gear pump comprising a housing having an inlet and an outlet and providing a gear pumping cavity consisting of a pair of intersecting bores, a liner complemen-,

tary in shape to said pumping cavity and providing a continuous tooth engaging surface on the inside of said pumping cavity, and said housing having a thin wall portion formed in said housing on the discharge side of said pump, said housing providing a pressure chamber behind said thin wall portion communicating with pump generated pressure to load said thin wall portion and said liner inwardly against the tips of the gear teeth for periph eral tooth sealing, said thin wall portion and said pressure chamber being spaced concentrically outwardly of said pumping cavity on the discharge side of the pump, and means limiting full discharge pressure to the area prescribed between two gear teeth immediately adjacent the outlet comprising passage means formed to communicate inlet pressure to the spaces between the other gear teeth toward the inlet side of the pump.

5. A gear pump comprising a housing having an inlet port and an outlet port and providing intersecting bores forming a pumping cavity, said cavity having a discharge zone remote from said inlet and communicating with said outlet, said housing including arcuate recesses formed therein spaced concentrically outwardly of said bo'res and extending from said discharge zone towards the inlet side outlet, said housing including movable wall means peripherally adjacent said bores and spaced from adjoining portions of said housing to form arcuate pressure chambers spaced concentrically outwardly of said bores and extending from said discharge zone towards the inlet side of the pump, meshing toothed gears in said bores for moving fluid from said inlet port to said outlet port, and means formed to communicate pump-generated pressure to said pressure chamber to load said Wall means inwardly for peripheral tooth loading, said mo vable wall means extending around said bores only adjacent said outlet ports at said discharge zone to seal against the tips of a predetermined number of gear teeth, and means to limit sealing of full discharge pressure to only said area prescribed between the gear teeth adjacent the outlet comprising passage means fo'rmed to communicate inlet pressure to the spaces between the other gear teeth.

7. A gear pump comprising a housing having an inlet port and an outlet port and providing intersecting bores forming a pumping cavity with a discharge zone remote from said inlet and communicating with said outlet, movable wall means peripherally adjacent said bores at said discharge zone and spaced from adjoining portions of said housing to form a pressure chamber, meshed toothed gears in said bores for moving fluid from said inlet port to said outlet port, and means formed to communicate pump-generated pressure to said pressure chamber to load said wall means inwardly for peripheral tooth loading, said movable wall means extending around said bores to seal against the tips of the gear teeth and means to limit sealing of full discharge pressure to only said area prescribed between gear teeth adjacent the outlet comprising means formed to communicate inlet pressure to the spaces between the other gear teeth, said last mentioned means comprising end plate means formed to provide a first sealing surface for the end of said pumping cavity and engaging an adjoining side of said gears and characterized by an arcuate circumferentially extending groove lying adjacent the gear teeth and in communication with said inlet port and with the spaces between the gear teeth on the inlet side of the pump.

References Cited in the file of this patent UNITED STATES PATENTS 164,147 Conver June 8, 1875 345,969 Harrold July 20, 1886 367,374 Deming Aug. 2, 1887 1,344,331 Carrey June 22, 1920 1,880,108 Ross Sept. 27, 1932 1,891,793 Kautlman Dec. 20, 1932 2,105,259 Oshei Fan. 11, 1938 2,211,154 Oshei Aug. 13, 1940 2,252,661 Oishei Aug. 12, 1941 2,504,230 Smith Apr. 18, 1950 2,622,534 Johnson Dec. 23, 1952 2,624,287 Ilyin Ian. 6, 1953 2,639,694 Johnson May 26, 1953 2,682,836 Orr July 6, 1954 2,742,862 Banker Apr. 24, 1956 FOREIGN PATENTS 625,405 Germany Feb. 8, 1936 

